Electrical conduit is used to mechanically protect electrical conductors. The U.S. National Electrical Code and Canadian Electrical Code require that explosion-proof enclosures housing arcing and sparking devices be sealed off to prevent propagation of flames or gases through the conduit system, and to minimize the explosion pressures. Such seals minimize the effects of pressure piling by acting as a barrier to stop burning gases from traveling through the conduit to other parts of the system.
When sealing conduit fittings, past methods utilize a fiber material that is weaved around each electrical conductor in the conduit to separate them. The fiber material is also packed in to form a dam at each end of a horizontal fitting, and at the bottom of a vertical fitting. A Portland type cement is then mixed with water and poured in through a funnel, puddled with a stick to remove air bubbles and left to cure for at least 24 hours.
The past methods were fairly labor intensive and error prone. Errors resulted when electrical conductors were not separated or fittings were not filled completely full with sealing compound. Further labor included obtaining clean water and mixing containers and the use of a stick to remove air bubbles.